Fire safety regulations, particularly those applicable to public buildings, impose strict requirements to be respected.
To this end, two criteria can be evaluated: Reaction to fire and resistance to fire, both codified on national and European levels.
Reaction to fire is the representation of a material as a combustible (combustibility, flammability), defined by the classification M in France and by the Euroclass classifications Ax sx dx in Europe.
Fire resistance is the time during which the construction element plays its role in limiting propagation.
The object of the present invention is to propose a slab that has good fire-resistant properties.
As indicated above, fire resistance indicates the time during which, during a fire, a construction element (wall, floor, ceiling, door, etc.) Retains its physical and mechanical properties. This material is classified into three categories:
mechanical strength or load-bearing capacity;
resistance to flames and to hot gases; and
Thermal insulation.
The French classification thus distinguishes three categories:
fire stability SF: the construction element maintains, during the time indicated, its load-bearing and self-supporting capacities;
fire integrity PF: the element is fire stable and prevents, during the time indicated, the propagation, to the unexposed side, of combustion gases and smoke; and
fire check CF: The element is fire resistant and prevents, during the time indicated, the propagation of heat to the unexposed side.
Thermal insulation corresponds to a maximum of 180° C. in a specific point, and to 140° C. on the entire surface (a door for example).
The SF, PF and CF criteria are noted in fractions of hours (¼ hour, ½ hour, ¾ hour, 1 hour, 1½ hour, hours, 2 hours, 3 hours, 4 hours, 6 hours). For example, “SF 2 hours” means fire stable for 2 hours.
The fire resistance Euroclasses are also distinguished into three classes:
R: mechanical strength or stability
E: resistance to gases and flames
I: thermal insulation (used when required in addition to an R or E classification)
These letters are followed by two or three numbers giving the resistance time in minutes. For example, <<REI 120>> means fire resistant for 120 minutes.
Intumescent materials are known that expand under the action of heat to form an insulating microporous foam called “meringue.” This protects the supports from flames, limits fire propagation and retards the temperature of materials from rising.
However, these materials are heavy and very expensive, therefore their usual modes of use are ill-adapted to protecting slabs from fire.
The object of the present invention is to mitigate this disadvantage.